If the velocity function is given by V(x) = 12x - 4x^2, find an equation of the tangent line to the graph of V(x) at (1, 8).

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Understand the Problem

The question asks to find the equation of the tangent line to the graph of the velocity function V(x) = 12x - 4x^2 at the point (1, 8). This involves finding the derivative of V(x), evaluating it at x=1 to get the slope of the tangent line, and then using the point-slope form of a line to find the equation of the tangent line.

Answer

$y = 4x + 4$
Answer for screen readers

$y = 4x + 4$

Steps to Solve

  1. Find the derivative of $V(x)$

To find the slope of the tangent line, we first need to find the derivative of the velocity function $V(x) = 12x - 4x^2$. We'll use the power rule.

$$ V'(x) = \frac{d}{dx}(12x - 4x^2) = 12 - 8x $$

  1. Evaluate the derivative at $x=1$

Now, we evaluate the derivative at $x=1$ to find the slope of the tangent line at the point $(1, 8)$.

$$ V'(1) = 12 - 8(1) = 12 - 8 = 4 $$

So, the slope of the tangent line is $4$.

  1. Use the point-slope form of a line

We have the point $(1, 8)$ and the slope $m = 4$. We can use the point-slope form of a line to find the equation of the tangent line:

$$ y - y_1 = m(x - x_1) $$

Plugging in the values:

$$ y - 8 = 4(x - 1) $$

  1. Simplify the equation to slope-intercept form

Now, we simplify the equation to the slope-intercept form ($y = mx + b$).

$$ y - 8 = 4x - 4 $$ $$ y = 4x - 4 + 8 $$ $$ y = 4x + 4 $$

$y = 4x + 4$

More Information

The tangent line to the graph of $V(x) = 12x - 4x^2$ at the point (1, 8) is $y = 4x + 4$. This line has the same slope as the curve at the given point and passes through that point.

Tips

A common mistake is to forget to add the $y_1$ value after distributing $m$ ($y - y_1 = m(x - x_1)$). Another mistake is incorrectly calculating the derivative.

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